Apparatus for detecting recurrent circuit operation



Patented Nov. 17, 1953 APPARATUS FOR DETECTING RECURRENT CIRCUIT OPERATION Arthur E. Dodd, Edgewood, Pa., assignor to Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application December 28, 1951, Serial No. 263,945

19 Claims. 1

My invention relates to apparatus for detecting recurrent circuit operation and particularly to improved means for detecting the recurrent operation of a contact in such manner that fail ure of any part of the apparatus will not result in an erroneous indication of the operating state of the contact.

It has heretofore been proposed to check the recurrent operation of a circuit, or a contact controlling a circuit, by providing a capacitor and a slow release relay, arranged so that energy is periodically supplied to the capacitor and thereafter supplied to the win-ding of the slow release relay, to energize the relay. The release time of the relay is selected. so that its contacts will remain picked up during intervals in which no energy is supplied to the winding from the capacitor. Such arrangements are characterized by liability to failure should the contacts which govern the switching of the capacitor from the source of energy to the winding of the relay become fused or otherwise deranged in such manner that the contacts are bridging, that is, so that the movable contact engages both stationary contacts at the same time. Should this occur, energy will be supplied directly to the winding of the slow release relay, so that the relay would be falsely energired.

Accordingly, it is an object of my invention to provide improved means for detecting recurrent operation of a circuit or a contact governing a circuit arranged so that defects in the contact will not result in improper energization of the code detecting means.

Another object of my invention is to provide improved means for detecting the code-following operation of a contact which may be subject to misalignment, sticking, etc., which might cause the movable member of the contact to simultaneouslv engage both of the associated stationary contacts.

Another object of my invention is to provide improved means for detecting recurrent operation of a contact or of a circuit element, in which the apparatus is arran ed so that any failure of the component parts will not result in improper energization of the relay which detects the recurrent'operation of the apparatus.

Still another object of my invention is to provide a nove1 and improved means for checking therecurrent supply of energy to a lamp or other load, where it is essential that all of the elements be arranged so that any possible failure will not cause an erroneousindication.

Other objects of my invention and. features 2 of novelty thereof will become apparent from the following description taken in connection with the accompanying drawing.

I shall describe two forms of code detecting apparatus embodying my invention and shall then point out the novel features thereof in claims.

In the drawings, Fig. l is a diagrammatic View of code detecting apparatus embodying my invention, as employed in connection with a coded track circuit railway signaling system.

Fig. 2 is a diagrammatic view of code detecting apparatus embodying my invention for checking the proper operation of a flashing electric lamp, to provide an indication of the operation thereof at a point from which the flashing electric lamp is controlled.

In the drawings, similar reference characters refer to similar parts in each of the two views.

In practicing my invention, 1 provide a capacitor to which energy is supplied when the contact which is recurrently operated is in one of its two positions, and from which energy is supplied to a slow release code detecting relay when the contact is in its other position, the detecting relay winding and capacitor being connected in series, and having an asymmetric unit, such as a rectifier or other similar device, for by-passing the winding of the relay during the charging period of the capacitor. The asymmetric unit is poled so that while the capacitor is discharging energy will flow through the winding of the slow release detecting relay causing it to pick up. This detector relay is slow in releasing so that its contacts will remain picked up during the intervals in which no energy is supplied to its winding. Moreover, the code detecting relay is of the biased type, in which the contacts will pick up when and only when current flows through the winding of the relay in a given direction. The relay is connected so that the ener y which may vi ow through its windin during the charging time of the capacitor will be in the direction opposite to that reouired to ick the relay contacts up. while the energ which flows through the relay during the discharging of the capacitor is in the proper direction to cause the contacts of the relay to pick up.

Referring to Fig. 1 of the drawings, there is shown a stretch of railroad track having track rails l and 3 which are divided by the usual insulated joints 5 into customary track sections. One complete section IT, and portions of adjoining sections are shown. Traffic normally moves from left to right in the track. stretch as indicated by the arrow, and a signal IS is located at the left hand or entrance end of section IT and governs entrance of trafiic into the section. At the right hand or exit end of the section, a contact of a continuously operating code transmitter 150T recurrently connects the track battery TB across the track rails at the exit end of section IT. The contact of code transmitter itCT may operate at any appropriate code speed, such as '75 times per minute, to thereby supply impulses of energy to the rails of section IT. At the entrance end of the section, a code following track relay ITR is connected across the track rails, and responds to the impulses of energy supplied thereto over the rails from the exit end of the section, causing its contact a to recurrently be operated between its release and picked up position, in response to the supply of impulses of energy to the winding of the track relay. The construction of the code transmitter 750T forms no part of my invention, and it will sufilce to say that the code transmitter is of the conventional type, well known in railway signaling systems, which recurrently operates its contact at a specified speed when energy is supplied thereto from a source of low voltage direct current. Energy for operation of the apparatus including the code transmitter HGT may be furnished by any suitable source of low voltage direct current, such as the battery LB shown, having its positive terminal designated by the reference character B and its negative terminal designated by the reference character N.

When the contact of code transmitter i5CT is closed and the section is vacant, energy from the battery TB picks up the contact of track relay lTR, with the result that energy is supplied from terminal B over front contact a of relay i-TR, to the left hand element of a capacitor Q, the other element of which is connected to the negative terminal N of the battery by a circuit which includes the asymmetric unit K and the winding of the detecting relay HR connected in multiple. The asymmetric unit K is poled so that energy will flow therethrough during the time in which the condenser Q has its left hand element con nected to the positive terminal of the battery, so that at this time, with the contact a of relay lTR picked up, the capacitor Q will be charged to the voltage of the battery LB, and as is well known the energy stored in the capacitor at this time will be equal to one-half the value of the capacity times the voltage squared. It will be noted that any flow of energy through the winding of relay HR at this time will be in the direction to prevent the relay from picking up, since this flow of current which of course, is negligible due to the shunting of the rectifier K, will be in the direction opposite the arrow shown on the winding of the detecting relay.

When the contact a of the code transmitter TBCT interrupts the connection of battery TB to the section rails, the track relay ITR at the other end of the section will release its contact a. At this time, a circuit is established for supplying the energy stored in capacitor Q to the winding of detecting relay HR. This circuit may be traced from the left hand element of capacitor Q over back contact a of relay lTR, through the winding of the detecting relay HR from left to right, to the right hand element of condenser Q. It will be apparent that the rectifier K is poled in such manner that no energy can flow therethrough at this time, so that the entire amount of energy previously stored in condenser Q is 4 discharged through the winding of the detecting relay HR, to thereby cause the relay HR to pick up.

During the next picked up period of the contact a of the track relay iTR, the circuit for supplying energy of the capacitor Q to the winding of the detecting relay is interrupted, and the air-- cuit for charging the capacitor Q from the direct current source is again established, as previously described. At this time the asymmetric unit K serves as a snubbing unit to retard the release of relay HR, since the induced energy which tends to flow from the winding of the detecting relay HR is of the polarity such that it circulates through the rectifier K, thereby delaying the decay of iiux in the magnetic structure of the relay HR, and thus delaying the release of the relay. The parts are proportioned and arranged so that the relay HR is rendered sufficiently slow in releasing so that its contacts will remain picked up during the intervals in which no energy is supplied to the winding of the relay from the capacitor Q.

As long as track relay ETR is responding to coded energy supplied over the rails of section ii the capacitor Q is charged during the picked up period of the track relay and the energy stored in the capacitor is supplied to relay HR during the released period of the track relay, so that the contacts of relay HR are maintained picked up at this time.

With the contact a of relay HR picked up, an obvious circuit is established for supplying en ergy to the green lamp G of signal is, to thereby indicate that the track section 51 is clear and that an approaching train may proceed into the section.

When a train enters section iT, the track relay ITR is shunted and ceases to respond to coded energy supplied over the section rails, so that its contact a releases and remains released and energy is no longer recurrently supplied to the capacitor Q from the direct current source. Accordingly, the energy stored in the capacitor dischcrges through the relay HR, after which the relay HR. is no longer supplied with energy and its contact a releases, thereby interrupting the supply of energy to the green lamp G of signal I S, and establishing a circuit for supplying energy to the red lamp R of the signal, so that signal is indicates that the section is occupied.

When the section 5T is vacated, the track relay TR is again operated by coded energy so that the capacitor Q is charged during the picked up periods of the relay and energy from the condenser is supplied to relay HR during the released periods of the track relay, with the result that relay HR. again picks up and establishes the circuit of the green lamp G, and extinguishes the red lamp R of the signal.

The equipment is arranged so that the relay HR. will not be picked up if the movable contact a of relay ITR engages both its front and back points of contact. Under these conditions, the terminals B and N of the source would be connected together by the contacts so that the supply of energy is shunted away from the capacitor Q and the relay HR, and accordingly the relay HR will be released.

If the capacitor Q breaks down so that a circult is established between its elements, no energy will be stored in the capacitor and therefore cannot be supplied from the capacitor to the relay HR so thet the relay is certain to release. If the capacitor breaks down, the relay HR will not be energized during the picked up period-of the track relay, since the flow of energy through thewinding of relay HR will be in the direction opposite to that required to pick the relay up, and" additiona'lly, the low resistance shunting efie'ct of the asymmetric unit K will cause only a very small portion of the total energy to flow through the winding of relay HR, as previously explained.

If the rsymmet'ric unit or rectifier K breaks down, it will form a low resistance shunt across the terminals of the winding of relay HR during the time energy is being supplied from the capacitor Q, so that insufficient energy will be supplied to the wind ng of relay HR to pick up the contacts of the relay. v

If the asymmetric unit or rectifier Kis open, energy will be supplied from left to right through the winding of relay HR during the released periods of track relay lTR, and when contact a oi relay ITR is picked up, the charging current for c: pacitor Q will flow through the winding of relay HR from right to le t. As a result of the'los's of the by-passing and blocking effect of rectifier K due to its being open circuited, the relay will not be picked on by the flow of energy to its Winding at this time. s

From the fore oing, it will be seen that the detecting relay HR is energized when and only when the track relay I'IR is operated by coded energy, so that its contacts is recurrentiy -pi'cl'zed up and released, but the relay'I-IR will not be energized if the front and back contacts of the relay overlap so as to engage the movable contact simultaneously, and in addition. the detecting relay HR will not be energized as the result of failure of any of the components. in luding'the ca acitor Q and the asymmetric unit K. Accordingly, any failure of the apparatus will result in the release of relay HR to cause the red lamp to be lighted and crnnot result in improper energi'z ation of relay HRwith consequent lighting of the green lamp of si nal IS. H

In si nalin circuits, it is son ieti'ines nece sary to check whether or not a load is bein recurrently sup lied with energy. As an example of this situation, an electric lamp is sometimes flashed to provide a certain type of. signal indication. and it is desirable to provide means for che king whether or not the lamp is actually flashing. In Fig. 2 of the drawings, there is shown an arran ement for checking the operation of a flashing electric lamp. which arran ement comprises a second embodiment of my invention.

Referr n to Fig. 2. there is shown a'control point as indicated by the dotted rectangle, from which point the flashing of an electric lamp BL is to be controlled and additions 11y, an indication to be prov ded when the lamp is actually flashing. The control of the electric lamp is provided by a flasher relay FR/which is governed byan obvious circuit in luding the control switch SW at the control point. When the sw t h SW' is closed, ener y is supplied to the winding of the flasher relay, and this relay, well known in the art, is of the type in which the contacts are 1"ecurrently opened and closed at a specified rate, for example, times per minute, when energyis suppl ed to the winding of the relay. Aswillbe seen from the drawings, each time the contacto of the flasher relay FR is picked up a circuit is established for supplying energy to the electric lamp EL. This circuit may be traced from terminal B, over front contact a of flasherrelay FR, and through the lamp EL to the negative terminal N of the source, so that each time that contact a is'pieked up, the electric lamp EL is lighted, and when the contact a of the flasher relay FR is opened, the lamp is extinguished. The apparatiis for checking the operation of the lamp EL includes the capacitor Q, connected in series with the w nding of a checking relay CR, which in turn has connected across it an asymmetric unit The checking relay CR has a contact a which when picked up establishes an obvious circuit for supplying energy to the indication lamp KE at the control point.

the normal condition, as shown in the drawings, the switch SW is opened, so that the flasher relay FR is deenergized and its contact a is opened. At this time, no energy is supplied to lamp EL, and no energy flows through the winding of the checking relay CR, so that its contact a is released and the indication lamp KE at the control point is extinguished. It will now be assumed that the operator at the control point desires to flash the lamp EL, and accordingly closes the switch SW to energize the flasher relay The recurrent operation of contact a of flasher relay FR will supply energy to the electr c lamp EL. Additionally, when contact a of relay FR isclosed energy is supplied from ternnnalB of the battery to the left hand element of the capacitor Q, the right hand element of wh ch is connected to terminal N of the source through the asymmetric unit K and the winding of relay CR in multiple. The asymmetric unit 1s poled so that the charging current of the capacitor will flow therethrough at this time. A small a'mount of current which is not carried by thefa's ymmetric unit K will also flow through the w nding of the checking relay from right to le f t hut as indicated on the drawings, this direction of current flow is op osite to that requ red to pick up the relay CR. When contact a of theiflasher relay opens, the supply of energy the lamp EL "is interrupted, and the lam is extingu shed. However, at this time a circuit is provided; for supplying energy which was prev ously stored in the capacitor Q through the electric lamp EL to the winding of the detecting relay GR. This circuit may be traced from the left hand element or capacitor Q, through the filamentof lamp EL, through the winding of the checking relay CR, from left to right to the right hand element of capacitor Q. i he flow of energy through the winding of the relay CR at th s time is in the proper direction to cause the contacts of the relay to pick up. Additionally, the parts are proportioned and arranged o that the current which flows through the filament of thelamp EL at this time is insufiicient to cause the lamp to become l ghted since the resistance of the relay limits the value o the discharge current of the condenser. The flow of energy at this time is in a direction opposite to that in which the asymmetric unit K is poled so that all the energy stored in the capacitor gigs discharged through the winding of the relay 6 V Vhen contact a of the flasher relay FR again is closed, energy is supplied to the filament of lamp EL, and the capacitor Q is a ain charged to the voltage of the direct curient source. During these charging intervals following the first interval, the rectifier K acts as a snub across the winding of relay CR since it is poled in such direction that the induced current W111 flow thercthrough, thereby delaying the decay of flux 1n the magnetic circuit of the relay The parts are proportioned and arranged so that the relay CR will maintain its contacts picked a up during the intervals in which no energy is thereby causing an open circuit at this point,

the lamp of course will be continuously extinguished, and although the contacts of the flasher relay FR will continue to supply charging energy to the capacitor Q, the discharge path of this energy will be interrupted, so that relay CR will release and remain released. Moreover, if for some reason or other, the contact a of the flasher relay FR, should remain in its picked up position, the lamp EL will be continuously lighted. However, since the capacitor Q will not have an opportunity to discharge its stored energy through the winding of relay CR, the contacts of relay CR will release to indicate that the lamp is not flashing properly. As pointed out in connection with Fig. 1, a failure of capacitor Q or the asymmetric unit K can only cause energy to be supplied through the winding of relay CR in the direction opposite to that required to pick up the relay, so that failure of these components will not cause improper indication.

It will be apparent from the foregoing that apparatus arranged in accordance with my invention as shown in Fig. 2, provides a re iable and economical arrangement for checking the recurrent supply of energy to a load device.

It will be apparent to those skilled in the art that the arrangement is not limited to checking the supply of energy to an electrc lamp, but may be employed to check the supply of energy to any type of load which develops a voltage drop tact code detection. That is, the res stor re places the lamp EL and furnishes a discharge path for the capacitor Q.

Although I have herein shown and described only two forms of apparatus embodying my invention, it will be apparent to those sk lled in i the art that various changes and modifications may be made ther in within the scope of the appended claims without departing from. the spirit and scope of my invention.

Having thus described my invention, what I:

claim is:

1. In combination, a contact adapted to be recurrently operated between a first and a second position, a source of electrical energy, a storage device capable of storing energy delivered thereto.

from said source, an asymmetric device, circuit means governed by said contact in one'oi its two positions for supplying energy from said source to said storage device through said asymmetric device in its conducting direction, a relay havingz-U contacts which are picked up when and only when energy flows through a winding of the relay in a given direction, said relay winding being connected in multiple to said asymmetric device so that energy which is supplied thereto in the nonconducting direction of said asymmetric device will flow through said winding in said given direction, and circuit means effective when said contact is in the other of its two positions for supplying energy from said storage device to said asymmetric device and said relay winding.

2. In combination, a contact adapted to be recurrently operated between a first and a second position, a source of electrical energy, a storage device capable of storing energy delivered thereto from said source, a rectifier, circuit means governed by said contact in one of its two positions for supplying energy from said source to said storage device through said rectifier in its conducting direction, a relay having contacts which are picked up when and only When energy flows through a winding of the relay in a given direction, said relay winding being connected in multiple to said rectifier so that energy which is supplied thereto in the non-conducting direction of said rectifier will flow through said winding in said given direction, and circuit means effective when said contact is in the other of its two positions for supplying energy from said storage device to said rectifier and said relay winding.

3. In combination, a contact adapted to be recurrently operated between a first and a second position, a source of electrical energy, a storage device capable of storing energy delivered thereto from said source, an asymmetric device, circuit means governed by said contact in one of its two positions for supplying energy from said source to said storage device through said asymmetric device in its conducting direction, a relay having contacts which are picked up when and only when energy flows through a winding of the relay in a given direction, said relay winding being connected in multiple to said asymmetric device so that energy which is supplied thereto in the non-conducting direction of said asymmetric device will flow through said winding in said given direction, circuit means effective when said contact is in the other of its two positions for supplying energy from said storage device to said asymmetric device and said relay winding, and circuit means governed by said relay.

4. In combination, a contact adapted to be recurrently operated between a first and a second position, a source of electrical energy, a, storage device capable of storing energy delivered thereto from said source, a rectifier, circuit means governed by said contact in one of its two positions for supplying energy from said source to said storage device through said rectifier in its conducting direction, a relay having contacts which are picked up when and only when energy flows through a winding of the relay in a given direction, said relay winding being connected in multiple to said rectifier so that energy which is supplied thereto in the nonconducting direction of said rectifier will flow through said winding in said given direction, circuit means effective when said contact is in the other of its two positions for supplying energy from said storage device to said rectifier and said relay winding, and circuit means governed by said relay.

5. In combination, a contact adapted to be recurrently operated between a first and a second position, a source of electrical energy, a capacitor capable of storing energy delivered thereto from said source, an asymmetric device, circuit means governed by said contact in one of its two positions for supplying energy from said source to said capacitor through said asymmetric device in its conducting direction, a relay having contacts which are picked up when and only when energy flows through a winding of the relay in a given direction, said relay winding being connected in multiple to said asymmetric device so thatv energy which is su plied thereto in the non-conducting direction of. said asyin metric device will flow through said winding in said given direction, and circuit means effective when said contact is in the other of its two positions for supplying energy from said capac tor to said asymmetric device and said relay winding.

6. In combination, a contact adapted to be re-. currently operated between a first and a second position, a source of electrical energy, a cat 9- itor capable of storing energy delivered thereto from said source, a rectifier, circuit means governed. by said contact in one of its two posit ons for supplying energy from said source to sa d capacitor through said rectifier in its G. iliQt ng direction, a relay having contacts w h are picked up when and only when energy now-s through a winding of the relay in a given direction, said relay winding being connected n multiple to said rectifier so that energy which s sup.- plied thereto in the non-conducting d re n of said rectifier will flow through said w nd ng n said given direction, and. circuit means efiective when said contact is in Jhe other of its two positions for supplying energy from said capacitor to said rectifier and said relay windin '7. In combination, a contact adapted to be recurrently operated between a first and a second position, a source of electrical energy, a capac tor capable of storing energy delivered 'tl drfito from said source, an asymmetric device, c rcuit means governed by said contact in one of its two positions for supplying energy from said source to said capacitor through said asymmetric device in its conducting direction, a relay hav ng contacts which are picked up when andonly when energy flows through a winding of the relay n a given direction, said relay wind ng being connected in multiple to said asymmetric device so that energy which is supplied thereto in the nonconducting direction of said asymmetr c device will flow through said Winding in said given direc-- tion, circuit means eiiective when saidccntact is in the other of its two positions for supplying energy from said capacitor to said asymmetric device and said relay winding, and circu t means governed. by said relay.

8. In combination, a contact adapted to be recurrently operated between a first and a second position, a source of electrical energy, a capacitor capable of storing energy delivered thereto from said source, a rectifier, circuit means governed by said contact in one of its two pos tions for supplying energy from said source to sa d capacitor through said rectifier in its conducting d rection, a relay having contacts which arepwked up when and only when ener y fiOWs through a winding of the relay in a given direction, sa d relay winding being connected inmultiple w th said rectifier so that energy which is suppl ed thereto in the non-conducting direction of sa d rectifier will flow through said winding in sa d given direction, circuit means effective when sa d contact is in the, other of its two positions for supplying energy from said capacitor to said rectifier and said relay winding, and circuit means governed by said relay.

9. In combination, a movable contact adapted to be recurrently operated between a first position in which it engages a first stationary contact and a second position in which it engages a second stationary contact, a source of direct current energy having a first and a second terminal, said first terminal of said source being connected to said first stationary contact, said "sec said second stationary contact, a capacitor, a

rectifier, circuit means for connecting said recti-p fier and said capacitor in series between said movable contact and said second terminal of said source, said rectifier being poled in a direction to permit charging current. to fiow to said capacitor from said source, and a relay having a winding connected across said rectifier, said relay having contacts which are picked up when and only when current flows through the winding of the relay in a given direction, said winding be! ing connected across said rectifier in such manner that the charging current of said capacitor which fiows through. the relay winding is ineifective to pick up the contacts of said relay.

10. In combination, a movable contact adapted to be recurrently operated between a first position in which it engages a first stationary contactand a second position in which it engages asecond stationary contact, a source of direct current ener y having a first and a second terminal, said first terminal of said source being connected to said first stationary contact, said second terminal of said source being connected to said second stationary contact, a capacitor, a rectifier, circuit means for connecting said rectifier and said capacitor in series between said movable contact and said second terminal of said source, said rectifier being poled in a direction to permit charging current to flow to said capacitor from said source, a relay having a winding connected across said rectifier, said. relay having contacts which are picked up when and only when current fiows through the winding of the relay in a given direction, said winding being connected across said rectifier in said manner that the charging current of said capacitor which flows through the relay winding is ineffective to pick up the contacts of said relay, and a circuit governed by the contacts of said relay. 7

11. In combination, a movable contact adapted to be recurrently operated between a first position in which it engages a first stationary contact and a second position in which it engages a sec ond stationary contact, a source of direct current energy having a first and a second terminal, said first terminal of said source being connected to said first stationary contact, said second terminal of said source being connected to said second stationary contact, a capacitor, an asymmetric device, circuit means for connecting said asymmetric device and said capacitor in series between said movable contact and said second terminal of said source, said asymmetric device being poled in a direction to permit charging current to flow to said capacitor from said source; and a relay having a winding connected across said asymmetric device, said relay having con; tacts which are picked up when and only when current fiows through the winding of the relay in a given direction, said winding being con-. nected across said asymmetric device in said manner that the charging current of said capac itor which flows through the relay winding is inefiective to pick up the contacts or said relay.

12. In combination, a source of direct current energy, a lead device adapted to be recurrently energized from said source, and means for detecting the recurrent energization of said load device, comprising a capacitor, an asymmetric device, circuit means for connecting said capaci tor and said asymmetric device in series across said load device, said asymmetric device being poled so that the capacitor is charged from said source each time said load device is energized from said source, and a relay having a winding connected across said asymmetric device, said relay having contacts which are picked up when and only when current flows through said winding in a given direction, said relay winding being connected so that the current which flows therethrough when said condenser is charging is ineffective to pick up the contacts of said relay.

13. In combination, a source of direct current energy, a load device adapted to be recurrently energized from said source, and means for detecting the recurrent energization of said load device, comprising a capacitor, an asymmetric device, circuit means for connecting said capacitor and said asymmetric device in series across said load device, said asymmetric device being poled so that the capacitor is charged from said source each time said load device is energized from said source, a relay having a winding connected across said asymmetric device, said relay having contacts which are picked up when and only when current flows through said winding in a given direction, said relay winding being connected so that the current which flows therethrough when said capacitor is charging is ineffective to pick up the contacts of said relay, a circuit governed by the contacts of said relay.

14. In combination, a source or" direct current energy, a load device adapted to be recurrently energized from said source, and means for detecting the recurrent energization of said load device, comprising a capacitor, a rectifier circuit means for connecting said capacitor and said rectifier in series across said lead device, said rectifier being poled so that the capacitor is charged from said source each time said load device is energized from said source, and a relay having a winding connected across said rectifier, said relay having contacts which are picked up when and only when current fiows through said winding in a given direction, said relay winding being connected so that the current which flows therethrough when said capacitor is charging is inefiective to pick up the contacts of said relay.

15. In combination, a source of direct current energy, a load device adapted to be recurrently energized from said source, and means for detecting the recurrent energization of said load device, comprising a capacitor, an asymmetric device, circuit means for connecting said capacitor and said asymmetric device in series across said load device, said asymmetric device being poled so that the capacitor is charged from said source each time said load device is energized from said source, a relay having a winding connected across said rectifier, said relay having contacts which are picked up when and only when current flows through said winding in a given direction, said relay winding being connected so that the current which flows therethrough when said capacitor is charging is ineffective to pick up the contacts of said relay, and a circuit governed by the contacts of said relay.

16. In combination, a source of direct current energy, a lamp adapted to be recurrently energized from said source, and means for detecting the recurrent energization of said lamp, comprising a capacitor, an asymmetric device, circuit:

means for connecting said capacitor and said 7 asymmetric device in series across said lamp, said asymmetric device being poled so that the capacitor is charged from said source each time said lamp is energized from said source, and a relay having a winding connected across said rectifier, said relay having contacts which are picked up when and only when current flows through said winding in a given direction, said relay winding being connected so that the current which flows therethrough when said capacitor is charging is ineffective to pick up the contacts of said relay.

17. In combination, a source of direct current energy, a lamp adapted to be recurrently energized from said source, and means for detecting the recurrent energization of said lamp, comprising a capacitor, an asymmetric device, circuit means for connecting said capacitor and said asymmetric device in series across said lamp, said asymmetric device being poled so that the capacitor is charged from said source each time said lamp is energized from said source, a relay having a winding connected across said rectifier, said relay having contacts which are picked up when and only when current flows through said winding in a given direction, said relay winding being connected so that the current which flows therethrough when said capacitor is charging is inefiective to pick up the contacts of said relay, and a circuit governed by the contacts of said relay.

18. In combination, a source of direct current energy, a lamp adapted to be recurrently energized from said source, and means for detecting the recurrent energization of said lamp, com prising a capacitor, a rectifier, circuit means for connecting said capacitor and said rectifier in series across said lamp, said rectifier being poled so that the capacitor is charged from said source each time said lamp is energized from said source, a relay having a winding connected across said rectifier, said relay having contacts which are picked up when and only when current flows through said winding in a given direction, said relay winding being connected so that the current which flows therethrough when said capacitor in charging is ineffective to pick up the contacts of said relay.

19. In combination, a source of direct current energy, a lamp adapted to be recurrently energized from said source, and means for detecting the recurrent energization of said lamp, comprising a capacitor, an asymmetric device, circuit means for connecting said capacitor and said asymmetric device in series across said lamp, said asymmetric device being poled so that the capacitor is charged from said source each time said lamp is energized from said source, a relay having a winding connected across said asymmetric device, said relay having contacts which are picked up when and only when current flows through said winding in a given direction, said relay winding being connected so that the current which flows therethrough when said capacitor is charging is inefiective to pick up the contacts of said relay, and a circuit governed by the contacts of said relay.

ARTHUR E. DODD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,010,840 Baughman Aug. 13, 1935 2,454,687 Baughman Nov. 23, 1948 2,461,452 Thompson Feb. 8, 1949 2,499,177 Baughman Feb. 28, 1950 

